astronomy

WD 0806−661

WD 0806−661 is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand WD 0806−661 rather than just read about it. In short: WD 0806−661 (L 97-3, GJ 3483), formally named Maru, is a DQ white dwarf with an extremely cold Y-type substellar companion (designated "B"), located in the constellation Volans at 62.7 light-years (19.2 parsecs) from Earth. The companion was discovered in 2011, and is the only known Y-type companion to a star or stellar remnant.

Key takeaways

WD 0806−661 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WD 0806−661 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WD 0806−661 from memory before moving on to harder problems.

Reference excerpt

WD 0806−661 (L 97-3, GJ 3483), formally named Maru, is a DQ white dwarf with an extremely cold Y-type substellar companion (designated "B"), located in the constellation Volans at 62.7 light-years (19.2 parsecs) from Earth. The companion was discovered in 2011, and is the only known Y-type companion to a star or stellar remnant. At the time of its discovery WD 0806-661 B had the largest actual (2500 AU) and apparent separation (more than 2 arcminutes) of any known planetary-mass object, as well as being the coldest directly imaged substellar object then known.

WD 0806-661 B

Component WD 0806-661 B was discovered in 2011 with the Spitzer Space Telescope. Its discovery was announced in the paper Luhman et al., 2011. The secondary has a mass between 7 and 9 MJ and a temperature between 325 and 350 kelvins (52 and 77 °C; 125 and 170 °F). At the time of its discovery, WD 0806−661 B was the coldest "brown dwarf" that has ever been found. The object is too faint to acquire a spectrum even with the Hubble Space Telescope, however the spectral type of this object was estimated to be Y1 based on its detection in Hubble images at near-infrared wavelengths. The photometric colors of this object suggest that it is metal-poor. The metal-poor composition of the companion could explain the DQ spectral type of the primary white dwarf. Hydrogen-deficient AGB stars might evolve into DB white dwarfs and then into DQ white dwarfs as they cool down. In August 2022, WD 0806-661 and its planetary-mass companion were included among 20 systems to be named by the third NameExoWorlds project. The approved names, proposed by a team from South Korea, were announced in June 2023. WD 0806-661 and its companion are named after the Korean words Maru (마루) and Ahra (아라).

See also List of exoplanets and planetary debris around white dwarfs WISE 0146+4234 – a Y0 companion to a T9 brown dwarf WISE 1217+1626 B – another Y0 companion to a T9 brown dwarf DT Virginis HD 106906 b GU Piscium b

Notes

References

External links Simbad — component b WD 0806-661 on Solstation.com

Illustrations

Worked examples

Example 1 — a first encounter with WD 0806−661

Start with the simplest possible case. Write down what WD 0806−661 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to WD 0806−661 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about WD 0806−661 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of WD 0806−661

In research: WD 0806−661 appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses WD 0806−661 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: WD 0806−661 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Binary stars, Gliese and GJ objects, Planetary systems with one confirmed planet, so understanding it makes those chapters shorter.
In everyday life: Look for WD 0806−661 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “WD 0806−661” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study WD 0806−661 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WD 0806−661 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain WD 0806−661 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WD 0806−661 in simple terms?

Why does WD 0806−661 matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study WD 0806−661?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on WD 0806−661.